Even outdated BlackBerrys can fetch £40 each on the black market in Africa, China and Europe because of the data they contain.

The age and model is not important to ID thieves.

Police forces in England and Wales recorded 14,980 robberies involving knives in the 12 months to June, up from 13,994 the previous year.

âWorryingly, a large proportion of phone owners still do not have passcodes on their phones, leaving them vulnerable to possible ID theft and fraud,â said Ch Con Jon Murphy.

The number of robberies without knives also rose by three per cent, from 74,887 to 76,786, the figures showed. That covers pick-pocketing, bag-snatching, theft of unattended property, shoplifting and bike theft.

The total for serious sexual crimes, including rapes and sexual assault, also went up, from 44,415 to 45,498.

However, the total number of crimes recorded by police fell four per cent to 4.1million in the year to June, down from 4.3million in the previous 12 months.

Asked about the rises in robberies with knives and burglaries, the prime ministerâs office said: âWhen you look at the individual categories, some of the changes are not necessarily statistically significant.â

Labourâs shadow home secretary Yvette Cooper said the rise was âextremely concerningâ and the coalition must âtake urgent action to cut crime instead of just cutting police.â